Compounds related to nucleosides: modified nucleosides (especially fluorescent), "stretched-out" nucleosides, and "abbreviated" dinucleosides will be made, tested for anti-viral and oncogenic activity, and converted to coenzyme and cofactor analogs to determine the requirements for hydrogen bonding and for the geometry of their interaction with specific enzymes. We will also synthesize and examine the spectra of a series of models for protein-nucleic acid interactions, e.g., by linkage of indole and purine or pyrimidine moieties through a trimethylene bridge or through the 1' and 5' positions of ribose. We will continue our work on the identification of the cytokinin-active nucleosides adjacent to the anticodon site in specific transfer ribonucleic acids from bacterial, mold, plant, and animal sources. In an exploration of the question of cell division and differentiation process, we will determine what modified ribonucleosides appear in tRNA, and how they are incorporated, when the applied cytokinin is unnatural and when it is natural. We will continue trying to improve on our anti-cytokinins, compounds which interfere with bacterial growth and other cell division processes. Finally, we will develop fluorescent, base-specific reactions and spray reagents for probing tRNA, viral RNA, other RNA structures, and chromosomes, and for effecting specific modifications including chemical mutations. BIBLIOGRAPHIC REFERENCES: Fluorescent modification of Guanine. Reaction with Substituted Malondialdehydes, R. C. Moschel and N. J. Leonard, J. Org. Chem., 41, 294-300 (1976). Fluorescent Cytokinins: Stretched-Out Analogs of N6-Benzyladenine and N6-(delta2-Isopentenyl)adenine, M. A. Sprecker, A. G. Morrice, B. A. Gruber, N. J. Leonard, R. Y. Schmitz, and F. Skoog, Phytochemistry, 15. 609-613 (1976).